Harden /submit route for production

- Defensive grid-to-coordinate resolution in create_qso (case instead of crash on match failure)
- Log warning when Oban weather enqueue fails instead of silently dropping
- Add 30s per-session submission cooldown to prevent rapid-fire submissions

lib/microwaveprop/radio.ex

@@ -137,17 +137,21 @@ defmodule Microwaveprop.Radio do
       grid1 = Ecto.Changeset.get_change(changeset, :grid1)
       grid2 = Ecto.Changeset.get_change(changeset, :grid2)
 
-      {:ok, {lat1, lon1}} = Maidenhead.to_latlon(grid1)
-      {:ok, {lat2, lon2}} = Maidenhead.to_latlon(grid2)
+      case {Maidenhead.to_latlon(grid1), Maidenhead.to_latlon(grid2)} do
+        {{:ok, {lat1, lon1}}, {:ok, {lat2, lon2}}} ->
+          distance = lat1 |> haversine_km(lon1, lat2, lon2) |> round() |> Decimal.new()
 
-      distance = lat1 |> haversine_km(lon1, lat2, lon2) |> round() |> Decimal.new()
+          changeset
+          |> Ecto.Changeset.put_change(:pos1, %{"lat" => lat1, "lon" => lon1})
+          |> Ecto.Changeset.put_change(:pos2, %{"lat" => lat2, "lon" => lon2})
+          |> Ecto.Changeset.put_change(:distance_km, distance)
+          |> Ecto.Changeset.put_change(:user_submitted, true)
+          |> Repo.insert()
 
-      changeset
-      |> Ecto.Changeset.put_change(:pos1, %{"lat" => lat1, "lon" => lon1})
-      |> Ecto.Changeset.put_change(:pos2, %{"lat" => lat2, "lon" => lon2})
-      |> Ecto.Changeset.put_change(:distance_km, distance)
-      |> Ecto.Changeset.put_change(:user_submitted, true)
-      |> Repo.insert()
+        _ ->
+          changeset = Ecto.Changeset.add_error(changeset, :grid1, "could not resolve grid to coordinates")
+          {:error, %{changeset | action: :insert}}
+      end
     else
       {:error, %{changeset | action: :insert}}
     end

lib/microwaveprop_web/live/submit_live.ex

@@ -6,6 +6,8 @@ defmodule MicrowavepropWeb.SubmitLive do
   alias Microwaveprop.Radio.Qso
   alias Microwaveprop.Workers.QsoWeatherEnqueueWorker
 
+  require Logger
+
   @band_options [
     {"1296 MHz", "1296"},
     {"2304 MHz", "2304"},
@@ -28,7 +30,8 @@ defmodule MicrowavepropWeb.SubmitLive do
        page_title: "Submit QSO",
        form: to_form(changeset),
        band_options: @band_options,
-       mode_options: @mode_options
+       mode_options: @mode_options,
+       submitted_at: nil
      )}
   end
 
@@ -42,18 +45,40 @@ defmodule MicrowavepropWeb.SubmitLive do
     {:noreply, assign(socket, form: to_form(changeset))}
   end
 
+  # Minimum milliseconds between submissions per LiveView session.
+  # For broader IP-based rate limiting, use a reverse proxy (nginx limit_req, Cloudflare).
+  @submission_cooldown_ms 30_000
+
   def handle_event("save", %{"qso" => qso_params}, socket) do
-    case Radio.create_qso(qso_params) do
-      {:ok, qso} ->
-        Oban.insert(QsoWeatherEnqueueWorker.new(%{}))
+    if recently_submitted?(socket) do
+      {:noreply, put_flash(socket, :error, "Please wait before submitting another QSO.")}
+    else
+      case Radio.create_qso(qso_params) do
+        {:ok, qso} ->
+          case Oban.insert(QsoWeatherEnqueueWorker.new(%{})) do
+            {:ok, _job} ->
+              :ok
 
-        {:noreply,
-         socket
-         |> put_flash(:info, "QSO submitted successfully!")
-         |> push_navigate(to: ~p"/qsos/#{qso.id}")}
+            {:error, reason} ->
+              Logger.warning("Failed to enqueue weather processing: #{inspect(reason)}")
+          end
 
-      {:error, changeset} ->
-        {:noreply, assign(socket, form: to_form(changeset))}
+          {:noreply,
+           socket
+           |> assign(submitted_at: System.monotonic_time(:millisecond))
+           |> put_flash(:info, "QSO submitted successfully!")
+           |> push_navigate(to: ~p"/qsos/#{qso.id}")}
+
+        {:error, changeset} ->
+          {:noreply, assign(socket, form: to_form(changeset))}
+      end
+    end
+  end
+
+  defp recently_submitted?(socket) do
+    case socket.assigns.submitted_at do
+      nil -> false
+      ts -> System.monotonic_time(:millisecond) - ts < @submission_cooldown_ms
     end
   end